A semiconductor device is described in International Publication No. WO2013/005474. The semiconductor device includes a semiconductor element, an insulated substrate on which the semiconductor element is disposed, and external connection terminals electrically connected to the semiconductor element via the insulated substrate. The insulated substrate includes an insulator layer, an inner conductor layer located on one side of the insulator layer and electrically connected to the semiconductor element, and an outer conductor layer located on the other side of the insulator layer. One end of the external connection terminal is joined to the inner conductor layer of the insulated substrate.